A magnetic recording apparatus as an example of a disk apparatus incorporates a magnetic disk in a case, a spindle motor which supports and rotates the magnetic disk, a magnetic head for reading/writing data from/to the magnetic disk, and a carriage assembly supporting the magnetic head so that the head can move relative to the magnetic disk. The head section of the magnetic head includes a magnetic recording head for writing and a reproducing head for reading.
To increase the recording density and capacity of a magnetic disk apparatus or reduce its size, magnetic heads for perpendicular magnetic recording have recently been proposed. In one such magnetic head, a recording head comprises a main pole configured to produce a perpendicular magnetic field, a write shield pole, and a coil. The write shield pole is located on the trailing side of the main pole with a write gap therebetween and configured to close a magnetic path that leads to a magnetic disk. The coil serves to pass magnetic flux through the main pole.
A magnetic recording head for high-frequency assist recording with a spin-torque oscillator provided between the main pole and the write shield (i.e., in the write gap) has also been proposed. The spin-torque oscillator is formed by stacking an oscillator layer, intermediate layer and spin injection layer, and is electrically connected to the main pole and the write shield.
In the magnetic recording head constructed as the above, the write gap length is determined from the total film thickness of the spin-torque oscillator. To enhance linear recording density, i.e., a recording resolution in the longitudinal direction of a track, it is necessary to narrow the write gap. However, in the above-mentioned structure, the write gap of the magnetic recording head cannot be set narrower than the total film thickness of the spin-torque oscillator, which makes it difficult to increase linear recording density.